1. Field of the Invention
The present invention relates to an inkjet recording apparatus of two-liquid type which records an image on a prescribed recording medium by using a first liquid containing a coloring material, and a second liquid containing no coloring material or a small amount of coloring material to prevent depositing interference.
2. Description of the Related Art
An inkjet recording apparatus of one-liquid type has been known, which uses an ink of radiation-curable type which is cured when irradiated with radiation, such as ultraviolet (UV) light, an electron beam (EB), or the like. Here, the electron beam (EB) is a flow of electrons imparted with a large energy by being accelerated by means of a high voltage.
Japanese Patent Application Publication Nos. 2004-18656 and 2004-42465 disclose that an ink of one-liquid type that contains a pigment and a radiation-polymerizable monomer, which is curable by irradiation of radiation, is cured by radiating an electron beam at an acceleration voltage of 10 kV to 150 kV, thereby implementing printing.
In the inkjet recording apparatus of one-liquid type which uses the radiation-curable ink, it is difficult to avoid depositing interference (i.e., coalescence of ink droplets on the recording medium). In view of these circumstances, an inkjet recording apparatus of two-liquid type has been developed. In the inkjet recording apparatus of two-liquid type, it is possible to prevent the depositing interference effectively in comparison with the inkjet recording apparatus of one-liquid type by depositing a liquid (hereinafter called “treatment liquid”) containing no coloring material or containing a coloring material of 0.1% by weight (wt %) or less, on the recording medium, before depositing the ink liquid.
However, in the case where an ultraviolet light source (such as a metal halide lamp) is used as the radiation source for curing the ink, although it is possible to prevent the depositing interference as described above, ink dots are liable to float and move on a film of treatment liquid, and there may arise problems that: the gravity centers of the ink dots move due to the heating of the recording medium when irradiated with the ultraviolet light; the ink dots are unintentionally expanded; and consequently, the image quality is degraded due to the movement of the gravity center or the unintentional expansion of the ink dots. Moreover, it is required to sufficiently fix the image on the recording medium.